The device of the invention involves the configuring of a deformable mirror such that it permits easy actuator replacement. This characteristic makes the invention applicable to high spatial frequency deformable mirrors such as are currently used in atmospheric correcting system (SAAO) and airborne laser weapon programs where the actuators are 7 mm apart. Furthermore, the invention enables the manufacturing of a deformable mirror to be more easily accomplished, so as to end up with controlled, robust joints on both sides of the actuator, and permits significantly less problems in actuator replacement from the completed unit.
The purpose of the invention is to overcome the short comings in the design of present deformable mirrors. The current state of the art suffers from actuator joints that separate because of poor bonds, and in addition, actuators are very difficult to replace, necessitating removal of the entire faceplate. This invention offers a more reliable joint, both in assembly and use, as well as the capability of replacing individual actuators without removing the entire face plate.
As discussed in U.S. Pat. No. 5,745,278, deformable mirrors primarily intended for use as a beam train optic, require frequency response, reliability, and low cost of manufacture as critical to the design, performance and usefulness. Thus the invention has particular usefulness in deformable mirrors that are used in adaptive optical systems. This would include low and high energy beam train configurations; that is, both in atmospheric correcting systems (SAAO) as well as laser weapon systems.
A deformable mirror which is used as a downstream optic in conjunction with a substantially larger optical system which is disposed upstream thereof must possess a high degree of sensitivity with respect to its ability to make highly minute adjustments to the reflective surface of the mirror. This is because such optical downstream mirrors represent the upstream optics in miniature. Such mirrors have a diameter in the range of five to fifteen inches, but for the larger sizes use on the order of about one thousand separate piezoelectric actuators to effect such adjustments is possible. As can be expected, the nearly one thousand piezoelectric actuators which are used, are highly miniaturized and make assembly and disassembly when necessary, of the approximately one thousand piezoelectric actuators with the deformable mirror, painstakingly tedious.
Current state-of-the art deformable mirrors, such as, SAAOs must be satisfied with degraded performance if any of their 941 actuators fail since they are very difficult to replace. This replacement includes a complete replacement of the optical faceplate, a very difficult process. It is known to mechanically decouple the nose of the actuator from the back of the face plate, such as by cutting it with a wire saw. Other techniques involve melting epoxy joints with the application of heat to remove actuators.
Thus an object of the invention is to permit easy replacement of actuators in deformable mirrors thus maintaining their required performance characteristics without degradation with reasonable cost and schedule impacts.
Accordingly, it is another object of the present invention to provide deformable mirror actuation using individual piezoelectric actuators connected via an epoxy bond to the reaction plate thereby permitting disassembly inherent in systems utilizing such actuators.
Yet still a further object of the invention is to provide a means of in situ actuator replacement.